11.Red blood cells in which the malarial-fever parasite resides are eliminated from a person's body after 120 days. Because the parasite cannot travel to a new generation of red blood cells, any fever that develops in a person more than 120 days after that person has moved to a malaria-free region is not due to the malarial parasite.Which of the following, if true, most seriously weakens the conclusion above?
（A） The fever caused by the malarial parasite may resemble the fever caused by flu viruses.
（B） The anopheles mosquito, which is the principal insect carrier of the malarial parasite, has been eradicated in many parts of the world.
（C） Many malarial symptoms other than the fever, which can be suppressed with antimalarial medication, can reappear within 120 days after the medication is discontinued.
（D） In some cases, the parasite that causes malarial fever travels to cells of the spleen, which are less frequently eliminated from a person's body than are red blood cells.
（E） In any region infested with malaria-carrying mosquitoes, there are individuals who appear to be immune to malaria.
12.Fact 1: Television advertising is becoming less effective: the proportion of brand names promoted on television that viewers of the advertising can recall is slowly decreasing.Fact 2: Television viewers recall commercials aired first or last in a cluster of consecutive commercials far better thanthey recall commercials aired somewhere in the middle.Fact 2 would be most likely to contribute to an explanation of fact 1 if which of the following were also true?
（A） The average television viewer currently recalls fewer than half the brand names promoted in commercials he or she saw.
（B） The total time allotted to the average cluster of consecutive television commercials is decreasing.
（C） The average number of hours per day that people spend watching television is decreasing.
（D） The average number of clusters of consecutive commercials per hour of television is increasing.
（E） The average number of television commercials in a cluster of consecutive commercials is increasing.
13.The number of people diagnosed as having a certain intestinal disease has dropped significantly in a rural county this year, as compared to last year, Health officials attribute this decrease entirely to improved sanitary conditions at water-treatment plants, which made for cleaner water this year and thus reduced the incidence of the disease.Which of the following, if true, would most seriously weaken the health officials' explanation for the lower incidence of the disease?
（A） Many new water-treatment plants have been built in the last five years in the rural county.
（B） Bottled spring water has not been consumed in significantly different quantities by people diagnosed as having the intestinal disease, as compared to people who did not contract the disease.
（C） Because of a new diagnostic technique, many people who until this year would have been diagnosed as having the intestinal disease are now correctly diagnosed as suffering from intestinal ulcers.
（D） Because of medical advances this year, far fewer people who contract the intestinal disease will develop severe cases of the disease.
（E） The water in the rural county was brought up to the sanitary standards of the water in neighboring counties ten years ago.
14.The price the government pays for standard weapons purchased from military contractors is determined by a pricing method called “historical costing.” Historical costing allows contractors to protect their profits by adding a percentage increase, based on the current rate of inflation, to the previous year's contractual price.Which of the following statements, if true, is the best basis for a criticism of historical costing as an economically sound pricing method for military contracts?
（A） The government might continue to pay for past inefficient use of funds.
（B） The rate of inflation has varied considerably over the past twenty years.
（C） The contractual price will be greatly affected by the cost of materials used for the products.
（D） Many taxpayers question the amount of money the government spends on military contracts.
（E） The pricing method based on historical costing might not encourage the development of innovative weapons.
15.Some who favor putting governmental enterprises into private hands suggest that conservation objectives would in general be better served if private environmental groups were put in charge of operating and financing the national park system, which is now run by the government.Which of the following, assuming that it is a realistic possibility, argues most strongly against the suggestion above?
（A） Those seeking to abolish all restrictions on exploiting the natural resources of the parks might join the private environmental groups as members and eventually take over their leadership.
（B） Private environmental groups might not always agree on the best ways to achieve conservation objectives.
（C） If they wished to extend the park system, the private environmental groups might have to seek contributions from major donors and the general public.
（D） There might be competition among private environmental groups for control of certain park areas.
（E） Some endangered species, such as the California condor, might die out despite the best efforts of the private environmental groups, even if those groups are not hampered by insufficient resources.